Conventional respirator assemblies may utilize a mask or face piece configured to fit over the head of a user and/or be worn by a user. Respirator assemblies may include an inlet or inhale port or fitting configured to allow air for breathing into the mask, and an outlet or exhale port configured to allow air to be exhaled from the mask. Exhale assemblies may be used to allow exhaled air out of the mask, while preventing or inhibiting the flow of air from a surrounding environment that has not been filtered to enter the mask via the exhale port and respirator assembly. Respirator assemblies may be configured to operate in a variety of modes, with a different type of air supply being provided to the mask in the different modes.
Various air supply systems may be configured for positive pressure operation, wherein a positive pressure (e.g., a pressure provided by air supplied from a tank) is maintained inside the confines of a mask, hood, or the like worn by a user. Other air supply systems may be configured for negative pressure operation, where a positive pressure is not maintained inside the mask and air is drawn from the outside by the unaided breathing of a user creating a negative pressure (relative to atmospheric pressure) within the mask. However, a single respirator assembly may not be appropriate for operation in both positive pressure and negative pressure modes of operation. For example, an exhale system configured to maintain positive pressure within the mask may be difficult to overcome by the unaided breath of a user using the system in a negative pressure mode of operation. As another example, an exhale system configured to be used in a negative pressure mode of operation (e.g., providing a resistance to exhaled air readily overcome by the unaided breath of a user) may allow for leakage from a positive pressure system. Modifying certain conventional exhale assemblies from configuration for one mode of operation (e.g., negative pressure operation) to a different mode of operation (e.g., positive pressure operation) may be complicated and not practically or reliably performed in the field.
Thus, under certain conventional approaches, if users are required to use both negative and positive pressure operation, the users may be required to carry both types of equipment on their attire. Switching from one mode to a different mode would then require a user to remove one respirator and replace with another. Such a switch may take place in a contaminated or otherwise hazardous embodiment, rendering the user vulnerable to environmental or other hazards.
Conventional switchable exhale systems also suffer from drawbacks. For example, conventional switchable exhale systems require the user to manually switch a system from negative pressure mode operation to positive pressure mode operation. In some conventional systems, a manual rotation motion may be utilized to apply a bias to a negative pressure exhale valve or by moving a biased exhaled valve onto a valve seat. Such systems rely on the user to remember to switch between the two modes. However, if the user somehow fails to switch from negative pressure operation to positive pressure operation, excess air will escape via the exhale system, depleting the air supply of the positive pressure supply system. The depletion of air may not be audible to the user, especially in a loud environment. Such manual rotational switching mechanisms may be difficult to locate and/or be difficult to manipulate by a user wearing gloves, for example.